Before 1970 surgeon's headlights comprised an incandescent bulb and some beam forming optics mounted on a headpiece fitted on the surgeon's head. They were much like a flashlight except the batteries were either spatially separated--not on the surgeon's head, or some other sort of power was supplied. The disadvantage of the bulb on the head was excess heat. Only about 2% of the power to the bulb was converted into useful projected beam illumination. The remainder heated the surgeon's head.
In the mid-seventies Applied Fiberoptics, Inc., of Southbridge, Mass., introduced a headlight system in which the incandescent light was removed from the surgeon's head. The light source was placed in a light source box and focused onto a fiberoptic "light pipe", which was an assembly of small glass fibers. This light pipe carried the illumination to the surgeon's forehead and an optical assembly formed a spot of light a couple of feet away.
The advantage of the this light pipe system was that the heat was dissipated somewhere else. Only the useful light was piped to the surgeon's head.
This light pipe is typically about 6 to 8 feet long and the actual cross section of the bundle of fibers is about 5 mm. The fibers are housed in a plastic jacket so the outside diameter of the pipe is about 10 mm.
The disadvantages of the light pipe system are the light pipe weighs about 270 grams and the weight increases with length. The short length tethers and confines the surgeon to a small area. The light pipe prevents anyone from walking in back of the surgeon. The headgear needs to hold the projected spot steady relative to the surgeon's head needs to be tightened fairly snug to prevent the pull of the pipe from moving it. After an hour or so the typical user has a headache.
The forces of the light pipe on the surgeon's head comprises a vertically downward force of about half the weight of the pipe and a force along the length due to the catenary. This increases dramatically as the arc gets tighter (straighter). Consequently, most surgeons allow the light pipe to drop down their back.
In the `drape down the back` configuration every time the surgeon's head moves in the nod direction, the friction of the light pipe on the back pulls against this motion and is distracting.
The weight of the headgear to carry the light pipe is about 200 grams. When the headgear is secured to the surgeon's head, an inward force of between one to five pounds is applied. Depending upon the position of the surgeon and the shape of the arc of the light pipe, the pull on the headgear ranges between 100 to 250 grams. Also, and perhaps most annoyingly, when the surgeon's head moves, i.e. from a static through a dynamic moving poition, there is an additional force or pull of .+-.30 grams to overcome the friction of the light pipe on the back.
These light pipes gained wide acceptance but are universally disliked by surgeons.
The present invention is a headlight system that brings the light in with a pipe overhead and then the pipe drops vertically downward to the surgeon. The light pipe can go down somewhat and then loop up. When the excess length, the surgeon's position and the point of ceiling attachment are properly adjusted, there is little downward pull, little frictional pull against the back and almost no catenary pull. As a consequence, the prior art headgear need not be used with its associated weight. The light pipe and associated optics can be secured to any head cover but preferably they are secured to the typical sanitary cap commonly referred to as a cap. The cap need not be held so tightly on the head. There is very little force to move it around. Also, the invention eliminates the prior art headgear and its associated weight.
In addition to bringing the light pipe downwardly to the surgeon's cap from an elevated position, a light pipe is used which results in a pull on the surgeon's cap of less than one gram versus the prior art pull of between 100 to 250 grams. Further, there is, when realistically viewed, no additional pull felt when the surgeon's head is moved.
Broadly the invention comprises a system which includes a light pipe having proximal and distal ends. A source of illumination is placed at the proximal end and beam-shaping optics are placed at the distal end. The light pipe comprises two sections, a first long light pipe which comprises more than 50% of the light pipe, and preferably at least 70% of the total length; and a second tethered light pipe which extends downwardly from the long light pipe. The long light pipe section extends into the operating area and is secured in a fixed elevated position. The tethered section hangs downwardly from the long light pipe and defines in part an umbilical. The distal end is secured to the surgeon's cap which cap also supports beam-shaping optics.
It is impractical to secure the light pipe to the ceiling every time the surgeon puts on the headgear. The invention in one aspect provides a "joint" or "disconnect" in the tethered light pipe. This joint or disconnect defines in the tethered light pipe two sections, a depending light pipe which extends downwardly from the long light pipe and a disposable light pipe attached to the surgeon's cap. Typically there is four feet or less of disposable light pipe attached to the surgeon's cap.
The typical ceiling height in surgery is 9 feet or more. With a four foot umbilicus and a six foot high disconnect, the surgeon can move around in a circle of six foot radius which is more leeway than with the prior art system. Also, people can walk in back of the surgeon.
In implementing the system of this invention, I have found a short arc Xenon lamp (made by ORC and by ILC) has a bright enough spot such that all the light necessary can be carried in a 2 mm or less fiber pipe--as opposed to the 5 mm used before. In fact, with 1 mm diameter light pipe, a 4 inch diameter spot of illumination can be provided. With this 1 mm diameter light pipe, a single plastic fiber with no jacket can be used. The weight of this pipe per unit length is about 1/40th the weight of the typical old light pipe used for this purpose.
This weight is almost unnoticeable on the surgeon's head and the cap is almost undisturbed by the pull. This allows the new system to mount the headlight on the sanitary paper surgeon's cap that the surgeon wears.
In addition, the beam-shaping optics is scaled down in proportion to the fiber bundle size. That is for a 1 mm fiber all dimensions of the optics can be scaled down by a factor of 5 from the one used with a 5 mm bundle of fibers. This is not a trivial advantage. The old optical assembly stuck out so far that the surgeon could not wear an ordinary face shield. The assembly got in the way. The new lens assembly is so small that it doesn't interfere with the use of an ordinary face shield.
With the system of the invention, the features of down-sizing, the use of the sanitary cap and the use of the disconnect, result in so little material used that the cap, beam-shaping optics and disconnect light pipe can be sold and used as a disposable headlight system. Generally, the disposable headlight system of the invention (from the disconnect onward) can be manufactured at less than 1/50th the cost of the old light pipe and headgear.
The advantage of disposability is that the disposable headlight system can be provided in a sterile condition. The old system provided a pipe that could be and was actually autoclaved by the hospital. The headgear itself was not autoclavable and generally was never washed, let alone sterilized and became increasingly filthy with dried patient's blood as it was reused.
With the light source used with the invention, an area can be illuminated bright enough to serve six 1 mm diameter pipes. Therefore, another aspect of the invention is an assembly of fibers that separate into several light pipes. The heat generated at the bright spot is intense so it is advantageous to use glass fibers (rods) in this assembly.
The separate light pipes extend from the source to several operating rooms. It is preferable to provide at least two headlights per procedure.
Broadly the invention comprises a surgeon's headlight system which has a light source, a light pipe having a proximal end in optical communication with the light source and a distal end in communication with beam-shaping optics. The distal end and the beam-shaping optics are secured to a surgeon's sanitary cap. The light pipe comprises a first long light pipe section which is secured in a fixed elevated position above the expected level at which the surgeon's head will be and a second tethered section which depends from the long section and defines along its length, at least in part, an umbilical.
In a preferred embodiment, the tethered section is characterized by a quick disconnect which defines a depending light pipe and a disposable light pipe secured to the surgeon's cap.
In a particularly preferred embodiment, the system of the invention comprises a manifold in communication with the light source, a plurality of long light pipes extending from the manifold to a plurality of locations where they are secured to the surgeon's headgear.
In still another embodiment, the plurality of light pipes extending from the manifold comprise two sections, first long light pipe sections secured in an elevated position and second tethered sections, the tethered sections having disconnects.